Initiative without rounds

I don’t use initiative in rounds.

I’d be glad for either being able to toggle the rounds on/off or have an initiative counter completely without it for avoiding accidental switching.

Albeit, my greatest wish would be an initiative system which allows math. For example, take all counters down/up for a number (GM), add/substract a value from own initiative, activate a button if the initiative reaches a certain value as 0 or 12…